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Biomedical subjects

M Massi-Benedetti

Publications and source records attributed to M Massi-Benedetti.

At least 19 recordsLinked to original sources

Pharmacology and clinical experience with repaglinide.

Repaglinide (NovoNorm((R))) is a novel oral antidiabetic agent, the first of a new class of insulin secretagogues known as the prandial glucose regulators to be approved for use in patients with Type 2 diabetes. Prandial glucose regulation is aimed at restoring the first-phase insulin response that follows consumption of a meal, which is missing in patients with Type 2 diabetes. After repaglinide administration, the resulting insulin profile reflects that of healthy individuals more closely, providing tighter glycaemic control and reducing the risk of hypoglycaemic events. Repaglinide is quickly absorbed and rapidly eliminated through biliary excretion, making it suitable for use in patients with renal impairment. It appears in the bloodstream within 15 to 30 min of dosing, stimulating short-term insulin release from the pancreatic beta-cells by binding to a unique site on the beta-cell membrane. Rapid elimination ensures that postprandial insulin levels quickly return to preprandial levels as the high prandial glucose level subsides. Repaglinide is given on a 'one meal, one tablet; no meal, no tablet' basis. It is particularly effective in patients who have not previously been treated with an oral antidiabetic agent, significantly reducing glycosylated haemoglobin (HbA(1c)) levels by 1.6%. It also offers increased mealtime flexibility and safety, compared with other oral antidiabetic agents. As a result of the short plasma half-life and lack of accumulation of repaglinide with repeated dosing, the risk of between-meal and nocturnal hypoglycaemia is substantially reduced compared with other oral antidiabetic agents. Repaglinide acts synergistically with metformin, consistently improving glycaemic control in patients who were insufficiently controlled by metformin alone. Results from recent studies have shown similar synergistic effects with neutral protamine Hagedorn (NPH)-insulin or troglitazone.

Animals↗

Cardiovascular risk factors in type 2 diabetes: the role of hyperglycaemia.

Macrovascular complications are the most important causes of morbidity, mortality and disability in people with Type 2 diabetes mellitus. Although other known risk factors for macrovascular disease (e.g. dyslipidaemia, hypertension, obesity) often co-exist, diabetes itself is an important risk factor for accelerated development of atherosclerosis. Hyperglycaemia, hyperinsulinaemia and insulin resistance may each play a major role in the onset and development of atherosclerotic disease, which causes arterial wall dysfunction, haematological disturbances and lipid abnormalities through two mechanisms: oxidative stress and non-enzymatic glycation. Hyperglycaemia induces damage to the endothelium through activation of mitogen-activated protein kinase, protein kinase C and transcription factor nuclear factor (NF)-kappaB and through increased levels of pro-adhesion proteins such as intracellular adhesion molecule (ICAM)-1. The arterial wall tone is shifted towards vasoconstriction by hyperglycaemia, which is also associated with vascular smooth muscle cell proliferation and increased intimal wall thickness. Alteration of the coagulation system towards thrombophilia is observed in Type 2 diabetes and a series of lipid abnormalities that facilitate the development of atherosclerosis is evident. In Type 2 diabetes, undiagnosed disease and unrecognized postprandial hyperglycaemia are becoming the most relevant issues in reducing the risk of vascular complications and cardiovascular mortality; improved glycaemic control may reduce the incidence of macrovascular complications.

Blood Coagulation Disorders↗

The effects of acute exercise on metabolic control in type II diabetic patients treated with glimepiride or glibenclamide.

The effects of exercise on metabolic control in type II diabetic patients given glimepiride or glibenclamide were studied in a multinational phase II clinical trial (14 centers in 4 countries). A total of 167 type II diabetic out-patients (117 men, 50 women) completed the trial as planned. The study was of parallel group, 2 x 2 factorial design: patients were first stabilized in a randomized, double-blind manner on 3 mg of glimepiride or 10 mg of glibenclamide treatment once daily over 14-28 days and were then assigned in randomized open fashion to a group with or without exercise. Exercise consisted of riding a bicycle ergometer for 1 hour at pulse rate 120 beats per minute. Three-hour blood glucose, insulin, and C-peptide profiles were made after the stabilization phase (baseline profiles) and 7 days later with or without exercise (endpoint profiles). Pairwise comparisons of changes in blood glucose AUC/1-3 h revealed a statistically significant decrease in patients who exercised vs those who did not, which was comparable for both sulfonylureas used. There was a statistically significant decrease in C-peptide AUC/1-3 h and insulin AUC/1-3 h in the glimepiride exercise group vs the glimepiride group without exercise. Physical exercise did not lead to statistically significant changes in C-peptide AUC/1-3 h and insulin AUC/1-3 h under glibenclamide treatment. In conclusion, a blood-glucose-lowering response to acute exercise was demonstrated in type II diabetic patients treated with either sulfonylurea, but a significant suppression of endogenous insulin secretion was observed for glimepiride only.

Adult↗

A chip card for patients with diabetes.

DIABCARD provides the specification for the core of a Chip Card Based Medical Information System (CCMIS) for the treatment of patients with chronic diseases. It will provide an instrument for assessing health care services, improve the links between health care providers and set up communication between the different levels of health care. It will therefore improve the quality of care and thus the life of patients with chronic diseases. DIABCARD concentrates on diabetes at the moment, the concept of the diabetes chip card will, however, be extendable to other chronic diseases.

Chronic Disease↗

An L-lactate sensor with immobilized enzyme for use in in vivo studies with an endocrine artificial pancreas.

We report the features of a sensor for determining L-lactate. An oxygen sensor, coupled to a nylon net with chemically bound L-lactate oxidase (EC 1.1.3.2), is inserted into an artificial pancreas (Biostator, Miles) "downstream" from the glucose sensor. We used the sensor to continuously monitor the L-lactate concentration in blood after a "glucose clamp" experiment with a diabetic patient. L-Lactate determinations in blood drawn from the patient every 15 min agreed well with results obtained by use of the L-lactate sensor.

Enzymes, Immobilized↗

The response of blood intermediary metabolite levels to 24 hours treatment with a blood glucose-controlled insulin infusion system in type 1 diabetes.

Blood intermediary metabolite and hormone concentrations have been assessed in 10 insulin-dependent diabetic patients on SC injection therapy and during 24 hr of relative normoglycaemia on an artificial pancreas (GCIIS). Mean blood lactate (0.96 +/- 0.07 mmol/l) and pyruvate (0.087 +/- 0.004 mmol/l) levels remained elevated compared to normal controls (0.76 +/- 0.04 and 0.064 +/- 0.003, p less than 0.05 and less than 0.001, respectively). No tendency was detected for these levels to regress towards normal over the 24 hr period on the GCIIS. Mean individual 24 hr blood lactate concentrations correlated significantly with mean free insulin levels (r = 0.85, p less than 0.002), but inversely with prior out-patient diabetic control (r = 0.64, p less than 0.05). The shape of the 24 hr profiles of blood lactate and pyruvate changed between SC therapy and the GCIIS, corresponding in both studies to the form of the free insulin profile. Blood alanine and glycerol profiles were not abnormal on either regime. Blood 3-hydroxybutyrate levels were abnormal on both SC therapy (0.16 1.14 mmol/l) and the GCIIS (0.15 1.20 mmol/l, controls 0.04 1.31 mmol/l), with concentrations on SC therapy correlating positively with previous control. Abnormalities of intermediary metabolite levels persist during feedback normalization of blood glucose levels, with evidence of influences from both prior diabetic control, and current insulin delivery.

3-Hydroxybutyric Acid↗

[Use of the endocrine artificial pancreas (GCIIS; Biostator) in heart surgery].

It is well known that deep hypothermia used in open-heart surgery is usually associated with a marked reduction in carbohydrate tolerance, especially dangerous in the diabetic patient, since it might result in severe metabolic complications, namely ketosis and hyperosmolar coma. In order to prevent the occurrence of such complications we treated an insulin-dependent diabetic patient undergoing cardiovascular surgery, with a feed-back insulin infusion operated by an artificial pancreas (GCIIS, Biostator). The Biostator was then used to perform a continuous (minute by minute) blood glucose monitoring in 2 more patients, a type II (non insulin-dependent) diabetic and a non diabetic. Blood samples were drawn sequentially in order to determine plasma free insulin concentration. The glycemic profile observed in the insulin-dependent diabetic under artificial pancreas treatment was similar to that in the non-diabetic. Plasma free insulin levels dropped near to zero during by-pass cooling, returning toward basal level during the rewarming phase. Such results are then discussed by the Authors and given a pathogenetic interpretation.

Blood Glucose↗

A comparison of the activity and disposal of semi-synthetic human insulin and porcine insulin in normal man by the glucose clamp technique.

The activity of semi-synthetic human insulin has been compared with porcine insulin in normal man using an euglycaemic glucose clamp at two different insulin infusion rates. In the two hour infusion insulin levels plateaued for both types of insulin at 44-48 mU/l (infusion rate 0.05 U kg body weight-1 h-1) and 22-24 mU/1 (0.02 U kg-1 h-1), giving identical metabolic clearance rates. The glucose delivery required to maintain euglycaemia in the second hour of insulin infusion was 13.9 +/- 2.1 g (mean +/- SEM) and 14.7 +/- 1.5 g (NS) at the lower dose for porcine and human insulins respectively, and 27.1 +/- 2.5 and 28.0 +/- 2.9 g (NS) at the higher dose. The potency ratio for human, compared with porcine, insulin was 1.06 +/- 0.12. No differences were seen in the time of onset of action of the insulins, serum half-life or distribution space. The responses of blood lactate, pyruvate, alanine, glycerol and 3-hydroxybutyrate were identical. No untoward reactions occurred. The activity and disposal of this semi-synthetic human insulin are indistinguishable from porcine insulin in normal euglycaemic man.

Adult↗

Improvement of artificial endocrine pancreas (Biostator; GCIIS) performance combining feedback controlled insulin administration with a pre-programmed insulin infusion.

It is well known that the glycemic control accomplished by the artificial endocrine pancreas (Biostator; GCIIS), requires an excessive insulin consumption. In order to improve the Biostator performance, we have studied 5 insulin dependent diabetic patients on anticipated automatic pre-programmed insulin infusion starting at the beginning of breakfast. Such an operating method allowed us to obtain a significant reduction in insulin requirements (from 17,3 +/- 2,2 U to 13,3 +/- 2,2 U), and a better glycemic control (MBG 98,7 +/- 5,4 vs 111,1 +/- 5,6; M 2,34 +/- 0,9 vs 6,96 +/- 1,7; delta G 43,8 +/- 3 vs 73,4 +/- 9,7), as compared to those observed under conventional feed-back control in relation to breakfast.

Adolescent↗

Circulating catecholamine and glucagon responses to insulin-induced blood glucose decrement in a patient with pheochromocytoma.

In a gastrectomized woman with an adrenal pheochromocytoma we observed hypertensive crisis in association with postprandial hypoglycemic episodes. To assess whether hypoglycemia could be responsible for the hypertensive crises, we measured circulating catecholamines and glucagon during an insulin-induced blood glucose decrement carried out by an artificial endocrine pancreas. When the blood glucose level reached 36 mg/dl, a severe hypertensive crisis occurred. At this time, circulating catecholamines increased 2-fold (norepinephrine, from 2200 to 3568 pg/ml; epinephrine, from 950 to 1750 pg/ml), while no changes in glucagon were observed. Our observation suggests that in patients with pheochromocytoma, hypoglycemia may trigger a marked release of catecholamines independent of glucagon secretion. This response probably is mediated by activation of the sympathetic nervous system. Our results also suggest that the pancreatic A-cell response to blood glucose decrement is totally suppressed in patients with pheochromocytoma by the chronically high levels of circulating catecholamines. Thus, hypoglycemia may be added to the list of other well known factors which may provoke hypertensive emergencies in patients with pheochromocytoma.

Adrenal Gland Neoplasms↗

Impaired subcutaneous absorption of insulin in 'brittle' diabetics.

Twenty-four hour plasma free insulin and blood glucose and intermediary metabolite profiles have been measured in 6 C-peptide deficient 'brittle' diabetic patients, during continuous sc and im insulin infusion. During sc infusion free insulin profiles were erratic and unpredictable. Mean 24 h blood glucose levels were raised at 12.6 +/- 2.1 (SE) mmol/l, and 3-hydroxybutyrate at 0.24 +/- 0.08 mmol/l. Blood lactate (1.88 +/- 0.18 mmol/l) and glycerol (0.084 +/- 0.007) were also elevated. Insulin (im) restored free insulin profiles to the normal pattern as found in 'stable' diabetics on sc infusion, with characteristic post-meal peaks (49 +/- 7, 103 +/- 35, and 95 +/- 34 mU/l) and stable night-time levels. Mean 24 h blood glucose was 6.7 +/- 1.1 mmol/l (P less than 0-.05 compared to sc infusion) and 3-hydroxybutyrate 0.07 +/- 0.02 mmol/l (P less than 0.05). Blood lactate (1.67 +/- 0.08 mmol/l) and glycerol (0.10 +/- 0.02 mmol/l) levels remained abnormal. The ratio of plasma free insulin to insulin dose administered was significantly higher during im infusion. In the 6 'stable' diabetics on sc insulin infusion good blood glucose control (7.1 +/- 0.9 mmol/l) was accompanied by clear post-prandial insulin peaks, and stable nocturnal levels. The results strongly suggest that in one category of 'brittle' diabetics there is defective and erratic sc insulin absorption.

3-Hydroxybutyric Acid↗

Counterregulatory hormones during moderate, insulin-induced, blood glucose decrements in man.

To verify whether a significant increase in levels of counterregulatory hormones occurs in the course of mild blood glucose decrements, we infused regular insulin iv over 65 min in two groups of healthy volunteers (group A, n= 7; group B, n = 6) at a constant rate (group A, 0.05 U/kg; group B, 0.025 U/kg). All subjects were connected to an artificial endocrine pancreas (Biostator) for continuous blood glucose (BG) monitoring. Plasma insulin, glucagon, and GH were determined by specific RIAs. Plasma norepinephrine, epinephrine, and cortisol were measured by sensitive fluorimetric methods. A moderate fall in BG occurred from 91 +/- 1.5 mg/dl (mean +/- SEM) to a nadir of 56 +/- 4.5 mg/ml at 45 min in group A and from 81 +/- 2.5 to a nadir of 64 +/- 4.9 mg/dl at 45 min in group B. In both groups A and B, the increases in plasma glucagon and catecholamine levels, which remained strictly in the physiological range, appeared concomitant and were significant at 45 min (P less than or equal to 0.05 vs. basal), while the increases in plasma cortisol and GH concentrations were clearly delayed. The increments for all counterregulatory hormones (expressed as the area to minutes ratio) except GH, were significantly greater in group A than in group B ( P less than or equal to 0.01). There was a significant correlation between these increases, including that of GH and the BG decrease, calculated in all subjects investigated. These results suggest that the mechanisms involved for the release of counterregulatory hormones such as glucagon, catecholamines, cortisol, and GH are very sensitive to a moderate decrease in BG concentration and that there is a close relationship between this hormonal response and the degree of the BG decrements obtained.

Adult↗

Glucose controlled insulin infusion system (Biostator) application during surgery for a presumed pancreatic microinsulinoma.

A glucose controlled insulin infusion system has been used during and after surgery for organic hyperinsulinism in a 37 year old woman. During surgery the system was used to monitor the blood glucose and, in order to avoid insulin hypersecretion, glucose was not infused. A strict correlation was observed between surgical procedures and metabolic behaviour, suggesting the resection of a microinsulinoma despite negative frozen section histology. After surgery plasma insulin was undetectable and an abnormal glycaemic level was observed during an IV glucose load. To ensure an adequate intake of fluid and calories 10% glucose was infused at a rate of 130 mg/min for 16h and blood glucose was clamped at 6.6 mmol/l by feedback insulin infusion. The gradual recovery of residual pancreatic tissue activity was demonstrated by the progressive decrease in exogenous insulin requirement, and confirmed by the normal glycaemic and insulinaemic response to an IV glucose load 20h after surgery.

Adenoma, Islet Cell↗

Clinical trial with porcine des-Phe B1 insulin. A comparative study with unmodified insulin on therapeutical efficacy, biological activity and immunogenicity.

Studies have been carried out in insulin-dependent diabetics of porcine Des-pheB1 insulin, which is an insulin analogue obtained by removal of the N-terminal aminoacid of the B chain. The therapeutic activity of Des-phe insulin (regular and semilinte preparations) was tested in a group of 24 insulin-dependent diabetics and compared with the unmodified parent compound. Both types of insulin, Des-phe and unmodified were chromatographically purified preparations. The mean daily blood glucose profile obtained with Des-phe insulin was slightly higher than that of unmodified preparations, while the mean blood glucose and the "M" index of Schlichtkrull were similar. The biological activity of regular Des-phe and its unmodified parent compound was evaluated in 6 further insulin-dependent diabetics, with the aid of an artificial endocrine pancreas. The insulin requirement to achieve an optimal metabolic control was 10% less with Des-phe insulin than with the unmodified preparation. The immunogenicity of Des-phe and unmodified insulins, tested by measuring plasma insulin antibody titres in diabetic patients either newly or already insulin treated, was comparable. However the binding capacity of 125I-Des-phe insulin to preexisting antibodies seemed to be less than that of unmodified 125I-insulin in patients previously treated with unmodified insulin. Finally Des-phe appeared able to correct promptly and completely the insulin-induced lipodystrophy of three insulin-dependent diabetics.

Adult↗